Gmc hub torquing specs

Written by manny jeter

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You should always tighten bolts with the right amount of torque. (car wheel wrench image by Christopher Dodge from Fotolia.com)

GMC produces engines for many different brands of cars and trucks. Pontiac, Chevrolet, GM, Buick, Cadillac and Oldsmobile have all featured engines built by GMC. A vibration damper controls the vibration of the crankshaft when the engine pushes out power. A damper flywheel is placed on the hub face of the vibration damper. Bolts go through rubber cones of the flywheel that allow limited friction between the crankshaft and damper flywheel.

Engines With Two Hubs of Torque

On the 2.8L 171ci V6 engine, the bolts connecting the crankshaft pulley to the vibration damper hub have 25 foot-pounds of torque, while the bolts connecting the vibration damper hub to the crankshaft have 75 foot-pounds of torque. For the 3.7L 225ci V6 engine, the bolts connecting the crankshaft pulley to the vibration damper hub have 22 foot-pounds of torque, while the bolts connecting the vibration damper hub to the crankshaft have 140 foot-pounds of torque.

Other Engines With Two Hubs of Torque

On the 2.5L 151ci V4 engine, the bolts connecting the crankshaft pulley to the vibration damper hub have 25 foot-pounds of torque and the bolts connecting the vibration damper hub to the crankshaft have 160 foot-pounds of torque. For the 3.4L 207ci V6 engine, the bolts connecting the crankshaft pulley to the vibration damper hub have 44 foot-pounds of torque, while the bolts connecting the vibration damper to the crankshaft have 79 foot-pounds of torque.

Engines with Multiple Steps of Hub Torque

The bolts on the 5.7L 346ci V8 engine have multiple steps of torque. An old bolt is first tightened with 240 foot-pounds of torque and then removed. A new bolt is then torqued with 37 foot-pounds in step one and 140 degrees in step two. For the 4.3L 262ci V6 engine, the bolts connecting the vibration damper hub to the crankshaft have 70 foot-pounds of torque.